Metal Removal from Wastewater by Bacterial Sorption : Kinetics and Competition Studies

• Published in: Environmental technology 2005-06, Vol.26 (6), p.615-624
• Main Authors: Kang, S.Y., Lee, J.U., Kim, K. W.
• Format: Article
• Language: English
• Subjects: Absorption; Adsorption; Applied sciences; Bacteria; Biological and medical sciences; Biological treatment of waters; BIOREMEDIATION; BIOSORPTION; Biotechnology; COMPETITION; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General purification processes; HEAVY METAL; Industrial applications and implications. Economical aspects; Kinetics; Metals - chemistry; Metals - isolation & purification; Pollution; PSEUDOMONAS AERUGINOSA; Pseudomonas aeruginosa - metabolism; Thermodynamics; Wastewaters; Water Pollutants, Chemical - isolation & purification; Water treatment and pollution
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2001.9619501

Biosorption has distinct advantages such as high efficiency and cost-effectiveness for removal of metal ions from wastewater. However, most studies of bacterial biosorption have focused on the removal of a single metal ion from aqueous solutions, even though natural water and wastewater rarely contain only one kind of heavy metal. This study investigated competitive biosorption of Co 2+ , Ni 2+ and Cr 3+ in different combinations at various concentrations under conditions of co-existence in a synthetic wastewater system utilizing the gram-negative bacterium Pseudomonas aeruginosa. In a binary system with Co 2+ and Ni 2+ , the presence of the same concentration of dissolved Ni 2+ led to a significant decrease in the amount of Co 2+ adsorbed onto cells when compared with a single Co 2+ system in which Ni 2+ was absent. This result is most likely due to the similar competitive affinity of these equivalent cations for sorption sites located on the cells of the bacterium. However, the presence of Cr 3+ with either Co 2+ or Ni 2+ led to a strong reduction in the uptake of each of these bivalent ions by cells, whereas Cr 3+ adsorption was unhindered. Cr 3+ also significantly inhibited the adsorption of both Co 2+ and Ni 2+ onto cells in a ternary system involving Co 2+ -Ni 2+ -Cr 3+ , with the order of preferential metal uptake being Cr 3+ > Co 2+ ≅ Ni 2+ . Removal efficiency of the heavy metals reached 100 % at low concentrations ([Cr 3+ ]=[Co 2+ ]=[Ni 2+ ]=20 μM) in a multi-metal system. The results of this study indicate that pre-determination of co-existing heavy metals in wastewater and examination of their competition for the sorption sites of biosorbents are required for the efficient removal of inorganic toxicants utilizing biosorption processes.